Methods, systems and computer program products for suspending packet-switched sessions to a wireless terminal

ABSTRACT

Methods, systems and computer program products are provided through which a wireless terminal participating in a packet-switched communications session may temporarily suspend the session, for example, upon receipt of an incoming circuit-switched call. The wireless terminal may notify a server associated with the packet-switched session of receipt of the incoming circuit-switched call, and may also notify the server when the packet-switched session may be resumed. In embodiments of the present invention implemented in GSM networks, one or more of the notification messages may be transmitted to the server over the SMS data bearer.

FIELD OF THE INVENTION

The present invention relates to wireless communications and, moreparticularly, to methods, systems and computer program products for usein wireless terminals that support packet-switched communications.

BACKGROUND OF THE INVENTION

Analog cellular telephone systems, such as AMPS, ETACS, NMT-450, andNMT-900, have long been deployed successfully throughout the world.Since the early 1990's, digital cellular telephone systems such as thoseconforming to the North American standard IS-54 and the European GlobalSystem for Mobile Communications (“GSM”) standard have been in service.More recently, a wide variety of wireless digital services broadlylabeled as PCS (Personal Communications Services) have been introduced,including advanced digital cellular systems conforming to standards suchas IS-136 and IS-95, lower-power systems such as DECT (Digital EnhancedCordless Telephone) and data communications services such as CDPD(Cellular Digital Packet Data). These and other systems are described inThe Mobile Communications Handbook, edited by Gibson and published byCRC Press (1996).

In most cellular radiotelephone systems, the cellular system sets up adistinct, full-duplex, circuit-switched channel for each standard voicetelephone call that is carried by the system. Depending upon thecellular system, this circuit-switched channel may be implemented, forexample, as an FDMA channel, a TDMA channel, a TDMA/CDMA channel, etc.The circuit-switched channel is established by the cellular network atthe time the call is initiated and is maintained until the call isterminated.

In recent years, various cellular telephone systems have implementedcapabilities for supporting additional types of communications. By wayof example, cellular systems that operate under the GSM standard mayprovide various packet-switched communications services that may beimplemented according to the General Packet Radio Service (“GPRS”)standards that are part of the GSM standard. Such packet-switchedcommunications services may include e-mail, web-browsing, instantmessaging and the like. Another communication capability that hasreceived increased interest in recent years is a “push-to-talk”capability. Push-to-talk refers to a “walkie-talkie” like feature wheretwo users (point-to-point talk) or a larger group of users (group-talk)may engage in instant communications. Once a push-to-talk communicationssession is established, participants in the session typically do notneed to dial a phone number to converse with other participants. Thecommunications session may be left open for extended periods of time,even if the participants are in stand-by mode (i.e., not actuallyconversing). When a participant chooses to converse with anotherparticipant of the push-to-talk session, they typically need only pushand hold a button on their cell phone (or other wireless terminal) andspeak into the microphone.

The Open Mobile Alliance (“OMA”) has established a working group that isin the process of defining a specification under which a push-to-talkcapability will be implemented for GSM and other cellular systems. Whilethere are potentially a variety of different ways that such apush-to-talk capability could be implemented, the OMA is definingspecifications whereby the push-to-talk capability will be implementedusing voice-over-IP resources that are transmitted over GPRS.Voice-over-IP (“VoIP”) refers to a form of packet-switchedcommunications capability that operates over the Internet Protocol(“IP”) to support voice communications. In a VoIP system, voicecommunications are digitized and transmitted in small data packets overa communications network to the intended recipients. The data packetsmay travel over different paths through the network and are reassembledinto their proper order at the destination so that they may be convertedback into an analog voice signal that may be played to the remote user.Under current OMA plans, on the cellular network side, GPRS will be usedto implement the VoIP push-to-talk capability. Wireless terminals thatimplement the push-to-talk capability will, therefore, have both acellular address and an IP address (URL).

The push-to-talk capability may be implemented as a half-duplex channelthat is shared by all of the participants of the push-to-talk session. Awireless terminal user may arrange for establishment of the push-to-talksession by, for example, dialing a number on the keypad of theircellular telephone (or other wireless terminal) that is associated withthe remote user to whom they wish to speak. The wireless terminal sendsa page to a network server notifying the network server of the requestfor establishment of a push-to-talk session. The network serverestablishes a push-to-talk session between the user and the remote user.The push-to-talk session may be established between two users(point-to-point) or between three or more users (group talk). The pushto talk session typically is maintained until it is terminated by one ofthe users.

Once the push-to-talk session has been activated, either participant maysend a floor request (a request to use the half-duplex channel) bypushing a button on their wireless terminal. The network server mayindicate that the floor request has been granted by, for example, anaudio tone. Once the user has been granted the floor he may broadcastspeech over the channel by talking while holding in the button. Releaseof the button acts to release the floor so that the half-duplex channelmay then be used by another participant to the call or remain idle.While the push-to-talk session is active, it provides the user andremote user(s) an instant talk capability for communicating with eachother.

Under the current plans of the OMA working group, the GPRS push-to-talktransport protocol will use the Session Initiated Protocol (“SIP”) andthe Session Description Protocol (“SDP”) for transmission of control andsignaling information, and will use the Real Time Protocol (“RTP”) fortransmitting data (i.e., the voice traffic). The Real Time ControlProtocol (“RTCP”) will be used to transmit floor request/notificationsignals (i.e., the signals that are sent when a user grabs the channelby pressing the push-to-talk button on the wireless terminal andreleases the channel by releasing the button) and the start/end burstpackets. The present OMA proposal is to implement the push-to-talkchannel using a 4.75 kbps adaptive multi-rate (AMR) coded speech datachannel, with other data rate channels to possibly be added later.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide methods for a wirelessterminal participating in a packet-switched communications session tosend notice of receipt of an incoming circuit-switched call. In thesemethods, a paging request associated with the incoming circuit-switchedcall is received at the wireless terminal. A server associated with thepacket-switched communications session is then notified that thewireless terminal has received the incoming circuit switched call.

In certain embodiments of the present invention, the incomingcircuit-switched call may be a circuit-switched call that is transmittedover a GSM network. In such embodiments, the notification to the servermay be accomplished by forwarding a notification message from thewireless terminal to the server over the data bearer for the circuitswitched SMS channel (“the SMS data bearer”). The notification messagemay be implemented, for example, as a text message or an e-mail message.The notification message may, alternatively, be forwarded to the servervia, for example, an IP level connection that uses the SMS data bearer.In still other embodiments, the notification message may be forwardedover a packet-switched channel before, during or after the wirelessterminal answers the incoming circuit-switched call (if the wirelessterminals support such a capability). Additionally, one or more remoteterminals may also be notified that the wireless terminal hastemporarily suspended participation in the packet-switchedcommunications session.

The initial notification message may include an identificationassociated with the wireless terminal and/or an estimate of the lengthof the incoming circuit-switched call.

Estimates of the length of the circuit-switched call may be obtained,for example, based on average call-length data stored at the wirelessterminal (which may be an average of all calls, a subset of all calls,all received calls, all calls coming from the number associated with theincoming circuit-switched page, etc.). The server associated with thepacket-switched communications session may also receive a notificationmessage upon termination of the incoming circuit-switched call at thewireless terminal. This notification may be forwarded, for example, overthe SMS data bearer and/or via the GPRS connection once such aconnection has been resumed.

Pursuant to further embodiments of the present invention, methods oftemporarily suspending a push-to-talk session established by acommunications server between a first wireless terminal and a secondwireless terminal are provided. In these methods, the first wirelessterminal suspends the push-to-talk session. The first wireless terminalfurther notifies the communications server that it has suspended thepush-to-talk session. This notification may be accomplished, forexample, by forwarding a notification message from the first wirelessterminal to the communications server over the GSM SMS data bearer. Thisnotification message may, for example, be an e-mail or a text message,or alternatively may be forwarded via an IP level connection.Subsequently, the first wireless terminal may reestablish thepush-to-talk session. These methods for temporarily suspending apush-to-talk session may also be used in group talk situations thatinvolve push-to-talk communications between three or more wirelessterminals.

While described above primarily with respect to methods, as will furtherbe appreciated by those of skill in the art, the present invention maybe embodied as methods, systems, wireless terminals and/or computerprogram products.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a network in which themethods, systems and computer program products of the present inventionmay be used.

FIG. 2 is a schematic diagram illustrating different connectivitiesbetween a wireless terminal and a push-to-talk server.

FIG. 3 is a diagram illustrating a message flow that may be used totemporarily suspend a push-to-talk communications session according tosome embodiments of the present invention.

FIG. 4 is a functional block diagram of a wireless terminal according tosome embodiments of the present invention.

FIG. 5 is a flow chart diagram illustrating operations for providingnotice of receipt of an incoming circuit-switched call according to someembodiments of the present invention.

FIG. 6 is a flow chart diagram illustrating operations for temporarilysuspending a push-to-talk communications session according to someembodiments of the present invention.

DETAILED DESCRIPTION

The present invention will now be described more fully with reference tothe accompanying drawings, in which exemplary embodiments of theinvention are shown. This invention, however, may be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein. Accordingly, while the invention issusceptible to various modifications and alternative forms, specificembodiments thereof are shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the invention to the particular formsdisclosed, but on the contrary, the invention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the claims. Like numbers referto like elements throughout the description of the figures. Also, asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

The present invention is described, in part, below with reference toblock diagrams and/or flowchart illustrations of methods, systems and/orcomputer program products according to embodiments of the invention. Itis understood that a block of the block diagrams and/or flowchartillustrations, and combinations of blocks in the block diagrams and/orflowchart illustrations, can be implemented by computer programinstructions. These computer program instructions may be provided to aprocessor of a general purpose computer, special purpose computer,and/or other programmable data processing apparatus to produce amachine, such that the instructions, which execute via the processor ofthe computer and/or other programmable data processing apparatus, createmeans for implementing the functions/acts specified in the blockdiagrams and/or flowchart block or blocks.

These computer program instructions may also be stored in acomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instructions whichimplement the function/act specified in the block diagrams and/orflowchart block or blocks.

The computer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer or other programmableapparatus to produce a computer-implemented process such that theinstructions which execute on the computer or other programmableapparatus provide steps for implementing the functions/acts specified inthe block diagrams and/or flowchart block or blocks.

As will be appreciated by one of skill in the art, the present inventionmay be embodied as a method, system and/or computer program product.Thus, the present invention may take the form of an entirely hardwareembodiment, an entirely software embodiment or an embodiment combiningsoftware and hardware aspects, which may be collectively referred toherein as a “circuit” or “module.”

It should also be noted that in some alternate implementations, thefunctions/acts noted in the blocks may occur out of the order noted inthe flowcharts. For example, two blocks shown in succession may in factbe executed substantially concurrently or the blocks may sometimes beexecuted in the reverse order, depending upon the functionality/actsinvolved.

FIG. 1 is a schematic diagram illustrating a network 100 in whichembodiments of the methods, systems and computer program products of thepresent invention may be used. As shown in FIG. 1, the network 100 mayinclude a plurality of wireless terminals 110, 112, 114. The “wirelessterminals” of FIG. 1 include, but are not limited to, terminals that areconfigured to communicate via a cellular wireless interface. However, itwill also be appreciated that in certain embodiments of the presentinvention the wireless terminals may be configured to communicate viaother wireless interfaces such as, for example, a wireless local areanetwork interface (WLAN), a Bluetooth interface, another RFcommunication interface, and/or an optical interface. Example wirelessterminals include, but are not limited to, a cellular wireless terminal;a personal communication terminal that may combine a cellular wirelessterminal with data processing, facsimile and data communicationscapabilities; a personal data assistance (PDA) that can include awireless transceiver, pager, Internet/intranet access, local areanetwork interface, wide area network interface and/or Web browser; and amobile or fixed computer or other device that includes a wirelesstransceiver. Moreover, while the exemplary embodiments of the inventiondescribed herein are primarily described in the context of a GSM/GPRScellular system, it will be appreciated that embodiments of the presentinvention may also be implemented in wireless terminals that areconfigured to communicate via a cellular communication link that mayinclude other protocols such as, for example, ANSI-136, enhanced datarates for GSM evolution (EDGE), code division multiple access (CDMA),wideband-CDMA, CDMA2000, UMTS and the like.

The exemplary network 100 illustrated in FIG. 1 includes a GSM/GPRSnetwork 120. As will be understood by those of skill in the art, theGSM/GPRS network 120 includes a plurality of network elements (notdepicted in FIG. 1) that enable cellular radiotelephone communicationsaccording to the GSM/GPRS standards. The wireless terminals 110, 112,114 communicate via wireless links with radio towers 122, 124, 126 whichserve as access points for the wireless terminals 110, 112, 114 to theGSM/GPRS network 120. The GSM/GPRS network 120 is connected to thePublic Switched Telephone Network (“PSTN”) 140, allowing communicationsbetween the wireless terminals 110, 112, 114 and fixed terminals 116(e.g., a landline telephone) that are connected to the PSTN 140. Asshown in FIG. 1, the GSM/GPRS network 120 is also connected to one ormore internet protocol networks 130, thereby providing for thetransmission of packet radio communications (e.g., e-mail messages, webbrowsing, instant messaging, etc.) between the wireless terminals 110,112, 114 and other devices such as servers/computers 118 that areconnected to the IP network 130.

As is also shown in FIG. 1, the network 100 may further include one ormore push-to-talk servers 150, 152. The push-to-talk servers 150, 152may be connected to the GSM/GPRS network 120 and/or the IP network 130.The push-to-talk servers 150, 152 run a push-to-talk application whichmay be used to establish and control push-to-talk communicationssessions.

As will be understood by those of skill in the art, wireless terminalshave differing capabilities in terms of their ability to simultaneouslysupport both circuit-switched and packet-switched communications. By wayof example, certain GSM terminals (e.g., Class-B terminals) can supportboth circuit-switched and GPRS (packet-switched) transports, but cannotsupport both transports simultaneously. A Class-B GSM terminal istypically configured so that, in standby mode, it monitors for bothcircuit-switched and packet-switched pages. If a page is received, theterminal switches to the appropriate mode (i.e., circuit-switched orpacket-switched) and responds to the page. Typically, once a Class-Bterminal is on a circuit-switched call, it ceases to monitor forpacket-switched pages until the circuit-switched call is terminated.However, while the terminal is on a packet-switched call, it maycontinue to monitor for circuit-switched pages and, upon receipt of sucha page, the terminal may automatically terminate the packet-switchedcall and switch to circuit-switched mode to establish thecircuit-switched call.

When a Class-B terminal is on certain types of packet-switched calls,such as receiving an e-mail message or web browsing, the automaticswitch-over to circuit-switched mode in response to receipt of acircuit-switched page may be seamless. The receipt of the e-mail messageis suspended for the duration of the circuit-switched call and may thenbe resumed once the circuit-switched call is completed. However, forother packet-switched applications such as, for example, push-to-talkcalls or instant messaging, the receipt of a circuit-switched call mayinterrupt an ongoing conversation between the user of the wirelessterminal and a remote user. Neither the push-to-talk server or the otherusers participating in the push-to-talk session are typically providedany indication as to why the conversation was interrupted, when and ifit can be resumed, or any other information. As a result, the remoteuser may spend time and use system resources trying to reestablish thepacket-switched communication during the time the wireless terminal ison the circuit-switched call.

Under the proposed push-to-talk capability for GSM, in response to theinitiation of the push-to-talk application at a wireless terminal, aregistration request is forwarded to a push-to-talk server. Thepush-to-talk server activates a PDP (Packet Data Protocol) context toestablish a GPRS connection between the push-to-talk server and eachwireless terminal that is to be part of the push-to-talk session. ThisGPRS connection carries both the SIP control messages that are used toestablish the push-to-talk session and the RTP voice data packets thatcomprise the push-to-talk call. The PDP context typically is kept alive,often for many hours, until the push-to-talk session is terminated byone of the users. Thus, the PDP context may provide the “always-on”connection that allows for the “instant talk” feature of thepush-to-talk communications capability.

When a Class-B GSM terminal is participating in a push-to-talk session,it may receive a circuit-switched page indicating that there is anincoming circuit switched call. If the Class-B terminal is in standbystate (i.e., not actually transmitting or receiving voice data packetsunder the PDP context), the terminal exits the packet-switched channeland switches to a circuit-switched channel to establish thecircuit-switched call. If the terminal is in an active state withrespect to the push-to-talk session (e.g., transmitting or receivingvoice data packets) at the time the circuit-switched page is received,some Class-B terminals are capable of listening for circuit-switchedpages (so that they can drop the packet-switched session and answer thecircuit-switched call) while other Class-B terminals are not (and thusmay miss the circuit-switched page). When the Class-B terminal switchesto the circuit-switched channel, the terminal suspends the GPRSconnection at the radio resource (“RR”) level, thereby ending datatransmissions between the terminal and the GPRS network over the GPRSconnection. However, the PDP context remains established between thepush-to-talk server and the wireless terminal at the GPRS SessionManagement layer. If the user of the wireless terminal accepts theincoming call, the wireless terminal remains on the circuit-switchedchannel until the end of the call. Upon termination of thecircuit-switched call, the GPRS connection at the RR level is resumedand the push-to-talk session may then continue.

The push-to-talk server may be unaware that the wireless terminal hassuspended the GPRS connection to answer the circuit-switched call. Assuch, the push-to-talk server may continue to transmit RTP voice packetsand/or SIP control packets to a wireless terminal that has suspended itsGPRS connection.

Other types of GSM terminals (e.g., Class-A and Dual Transfer Modeterminals) can typically simultaneously support both circuit-switchedand packet-switched communications. As such, these terminals generallydo not have to suspend an established GPRS session when responding to acircuit-switched page. Thus, a user of a Class-A GSM terminal may beable to simultaneously hold a circuit-switched call whilesending/receiving e-mail and/or browsing the internet. However, evenwith Class-A and Dual Transfer Mode GSM terminals, a user typicallycannot simultaneously listen to or talk on a circuit-switched call and apush-to-talk communications session as these terminals generally haveonly a single user interface (e.g., speaker, microphone, etc.) which canonly serve one call at a time. For example, a user who attempted tolisten to both sessions simultaneously would create a time conflictcaused by overlapping usage of a common speaker on the wirelessterminal.

Methods, systems and computer program products are disclosed herein fora wireless terminal that is communicating over a packet-switched sessionto provide notice of receipt of an incoming circuit-switched call. Forexample, pursuant to some embodiments of the present invention, awireless terminal that is participating in an ongoing packet-switchedsession may notify a server that is associated with the session that thepacket-switched session is to be suspended. The notification may furtherprovide information regarding the reason prompting suspension of thepacket-switched session such as, for example, receipt of acircuit-switched page by the wireless terminal. In some embodiments ofthe present invention, the packet-switched server may further notify oneor more remote wireless terminals, servers and/or other devicesregarding suspension of the packet-switched session. In this manner,uncertainty which may result from the abrupt termination of thepacket-switched session and the possible waste of system resources inefforts to prematurely reestablish the call may be reduced and/oravoided altogether.

In certain embodiments of the present invention, a circuit-switchedconnection may be used to provide the notification message from thewireless terminal to the packet-switched server. By way of example, inthe GSM system, the notification message may be transmitted over theShort Message Service (“SMS”) data bearer. The SMS data bearer is thecircuit-switched connection that is used to transport the Short MessageService messages that are provided for under the GSM standard. The SMSdata bearer can coexist with the channels used to support bothcircuit-switched voice calls (e.g., the TCH channel) andcircuit-switched control signals (e.g., the SDCCH channel). Thus, theSMS data bearer provides a mechanism whereby the wireless terminal cansend a notification message to the packet-switched server whileresponding to the incoming circuit-switched page and/or answering theincoming circuit-switched call.

In some embodiments of the present invention, the packet-switchedsession may be a push-to-talk session that has been initiated by a userof a GSM/GPRS wireless terminal and that was established by apush-to-talk server. In response to receiving a circuit-switched page,the wireless terminal via, for example, a push-to-talk application thatis running on the terminal, notifies the push-to-talk server that thepush-to-talk session is to be temporarily suspended. This notificationmay be forwarded, for example, as either a text message or an e-mailmessage that is transmitted over the SMS data bearer. The message mayinclude, for example, an identifier associated with the cellulartelephone (e.g., a push-to-talk client ID), identification of the reasonthe push-to-talk session is being suspended, the expected interval ofthe suspension, etc. If other participants in the push-to-talk sessionattempt to communicate with the wireless terminal over the push-to-talksession during the period when the wireless terminal has suspended thesession, the push-to-talk server may notify those participants that thewireless terminal is temporarily unavailable. In other embodiments ofthe present invention, such notice may automatically be provided inresponse to the push-to-talk server receiving notification that aterminal has temporarily suspended participation in an on-goingpush-to-talk session. The notification to other participants in thepush-to-talk session, if provided, may be generated and forwarded by thewireless terminal and/or the push-to-talk server.

In other embodiments of the present invention, the notification messagemay be transmitted from the wireless terminal to the push-to-talk servervia an IP-level connection (UDP/IP) using the SMS data bearer (asopposed to GPRS) as the transport mechanism. In such embodiments, themessage is forwarded just like the other signaling and data packetsexcept that the SMS data bearer is used.

In additional embodiments of the present invention, the notificationmessage may be sent over the push-to-talk session (i.e., a GPRS linkinstead of, for example, the SMS data bearer) before the wirelessterminal switches to respond to the circuit-switched page. In suchembodiments, the notification message may, for example, be sent as acontrol message in the GPRS push-to-talk session as soon as the wirelessterminal senses an incoming circuit-switched page. Once the notificationmessage is sent, the wireless terminal may suspend GPRS operations andproceed to respond to the incoming circuit-switched page. Suchembodiments of the present invention may be of particular interest withClass-B GSM terminals or other terminals that may not simultaneouslysupport both circuit-switched and packet-switched communications.

In still further embodiments of the present invention, the notificationmessage may be sent over a GPRS link during and/or after the wirelessterminal responds to the circuit-switched page. This implementation maybe of particular interest with Class-A and/or Dual Transport Modeterminals as such terminals can send data over the GPRS link during acircuit-switched call, and as it eliminates the need for the terminal tosimultaneously handle two voice calls over circuit-switched connections.

The push-to-talk server may also be notified upon termination of thecircuit-switched call. This may be accomplished, for example, by thewireless terminal forwarding a notification message via the SMS databearer and/or through the GPRS bearer after the GPRS connection isresumed.

FIG. 2 is a schematic diagram illustrating different methods that may beused for transporting notification messages pursuant to certainembodiments of the present invention. As shown in FIG. 2, a GSM cellulartelephone or other wireless terminal 200 may communicate via circuitswitched calls with other devices over a GSM network 202. The wirelessterminal 200 also communicates with a GSM Simple Message ServiceController (“SMSC”) 204 over an SMS data bearer 206. The GSM SMSC 204communicates with a server 212 that controls a packet-switched session(in the example of FIG. 2, the application is a push-to-talk session).As shown in FIG. 2, this communication may be carried out via an IPlevel connection 208 over an IP network 210. The wireless terminal 200may also maintain an IP level connection 214 with the IP network 210. Inembodiments of the present invention, this IP connection 214 may becarried over the GSM SMS data bearer via the GSM SMSC 204. A UDP layerconnection 216 and SIP/RTP layer connections 218 may also be establishedbetween the wireless terminal 200 and the push-to-talk server 212.Finally, a push-to-talk connection 220 may be established between apush-to-talk client application that may be running on the wirelessterminal 200 and a push-to-talk server application that is running onthe push-to-talk server 212.

FIG. 3 illustrates an exemplary message flow according to someembodiments of the present invention that may pass between a wirelessterminal and other network and/or remote devices when the wirelessterminal suspends a push-to-talk session in order to receive acircuit-switched call. As shown in FIG. 3, a push-to-talk application or“client” 300 may be resident on a wireless terminal 310. Thepush-to-talk client may include a control plane 302 (i.e., a capabilityto forward and receive control messages/information) and a user plane304 (i.e., a capability to forward and receive push-to-talkcommunications or “media data”). As further shown in FIG. 3, thewireless terminal 310 may communicate over a circuit-switched SMS(“CS-SMS”) data bearer 312, a circuit-switched channel 314, and over aGPRS packet-switched channel 316. The wireless terminal 310 and thepush-to-talk client 300 communicate with a GSM/GPRS network 320 and witha push-to-talk server 330. The GSM/GPRS network 320 supports GPRS,circuit-switched and SMS traffic. The push-to-talk server 330 mayinclude a control plane 332 and a user plane 334.

As shown in FIG. 3, the push-to-talk client 300 (which is running on thewireless terminal 310) may initiate establishment of a push-to-talksession via an invitation 340. In response to the invitation 340, thewireless terminal 310 transmits an Active PDP Context Request 344 to theGSM/GPRS network 320 to establish a PDP context that may be used tosupport an IP connection between the wireless terminal 310 and thepush-to-talk server 330. The GSM/GPRS network 320 transmits an ActivePDP Context Accept message 348 to the wireless terminal 310 notifyingthe wireless terminal that the PDP Context Request has been accepted.The wireless terminal 310 then forwards an invitation request message352 to the push-to-talk server 330 over the IP connection, and thepush-to-talk server 330 establishes the push-to-talk session. Thepush-to-talk server 330 may also forwards an invitation acceptancemessage 356 that the registration was successful to the push-to-talkclient 300. Once the session is established, the push-to-talk client 300may transmit and receive media data 360 with the other user(s)participating in the push-to-talk session via the push-to-talk server330. The push-to-talk client 300 and the push-to-talk server 330 mayalso exchange control data 364 while the push-to-talk session is active.

As shown in FIG. 3, during the push-to-talk session, the wirelessterminal 310 may receive a circuit-switched page 368. In response tothis circuit-switched page 368, the wireless terminal 310 may send aGPRS suspend notification 372 to the GSM/GPRS network 320. Thisnotification 372 notifies the GSM/GPRS network 320 that GPRScommunications (i.e., the push-to-talk session) are being suspended.Additionally, the push-to-talk client 300 may forward a push-to-talk(“PTT”) temporary inactive notification 374 of the temporary suspensionof the push-to-talk session to the push-to-talk server 330. Thisnotification may be sent before, during, or after the GSM/GPRS network320 and the wireless terminal 310 set-up and connect the circuitswitched call 376. After the circuit switched call is completed, it iscleared 380. At this point, an “end suspension” notification 380 may beforwarded from the push-to-talk client 300 to the push-to-talk server330 to notify the push-to-talk server 330 that the temporary suspensionof the push-to-talk session is over. The GPRS sessions are resumed 382.Media data 388 and control data 392 may be exchanged between thepush-to-talk client 300 and the push-to-talk server 330 with resumptionof the push-to-talk session.

The notification message 374 that is forwarded from the push-to-talkclient 300 to the push-to-talk server 330 may be implemented in avariety of ways. As noted above, in certain embodiments of the presentinvention, it may comprise an e-mail or text message that providesspecified information regarding the suspension of the packet-switchedsession. In other embodiments, the notification message may, forexample, comprise digital or alphanumeric codes that serve to notify thepush-to-talk server and/or other devices that the wireless terminal istemporarily suspending participation in the packet-switched session.

FIG. 4 is a block diagram of an exemplary wireless terminal 400according to some embodiments of the present invention. The wirelessterminal 400 includes a processor 406, a transceiver 408 (that includesa transmitter 424 and a receiver 426), a packet-switched suspensionnotification circuit controller 410, a packet-switched communicationscircuit 430, a circuit-switched communications circuit 432, a memory414, a speaker 416, a microphone 418, a display 420, and a keypad 422,which may be at least partially within a housing 412. Thepacket-switched suspension notification circuit 410 may, for example,comprise part of the packet-switched communications circuit 430 or thecircuit-switched communications circuit 432

The memory 414 may include one or more erasable programmable read-onlymemories (EPROM or Flash EPROM), battery backed random access memory(RAM), magnetic, optical, or other digital storage device, and may beseparate from, or at least partially within, the processor 406. Theprocessor 406 may include more than one processing component, such as,for example, a general purpose processor and a digital signal processor,which may be enclosed in a common package or separate and apart from oneanother. The transceiver 408 typically, but not necessarily, includesboth a transmitter 424 and a receiver 426 to support two waycommunications. The wireless terminal 400 may, thereby, communicate witha wireless communications network using radio frequency signals. Theradio frequency signals may be communicated through an antenna 428according to one or more cellular communication protocols.

The packet-switched suspension notification circuit 410 may be used togenerate notification messages that notify a packet-switched server thatthe wireless terminal is temporarily suspending a packet-switchedcommunications session. In embodiments of the present invention, thepacket-switched suspension notification circuit 410 may be implementedas a software program or routine that runs on the processor 406 thatgenerates notification messages that may be forwarded when the wirelessterminal 400 temporarily suspends a packet-switched session. Thenotification messages may be pre-selected messages that are stored inthe packet-switched suspension notification circuit 410 and/or in thememory 414 or in another location within the wireless terminal 400, orthey may be messages that are generated based on specific attributes ofeach particular suspension. Moreover, as discussed above, thenotification message need not be a text or e-mail message, but may alsobe, for example an audio tone or an alphanumeric code that conveysinformation regarding the wireless terminal 400 temporarily suspendingone or more packet-switched sessions.

FIG. 5 is a flow chart illustrating operations through which networkelements may be notified that a wireless terminal 400 that isparticipating in a packet switched communications session has receivedan incoming circuit-switched call. As shown in FIG. 5, operations maybegin with the wireless terminal 400 receiving a page indicating thatthe wireless terminal 400 has received an incoming circuit-switched call(block 502). Upon receiving the page, the wireless terminal 400 maysuspend the packet-switched communications session (block 504) in orderto answer the incoming circuit-switched call. As discussed above,depending, for example, on the capabilities of the wireless terminal 400and the type of packet-switched communications session that is ongoing,suspension of the packet-switched session may or may not be necessary.The wireless terminal 400 also generates a notification message that isforwarded to a network server associated with the packet-switchedcommunications session (block 506). This notification message may notifythe server that the wireless terminal 400 has temporarily suspendedparticipation in the ongoing packet-switched communications session. Thenotification message may include further information such as, forexample, an identifier associated with the wireless terminal 400 withrespect to the ongoing packet-switched communications session, thereason for the temporary suspension of the session, an estimated lengthof the suspension period or the like. As discussed above, in certainembodiments of the present invention the operations at block 506 may beperformed in advance of the operations at block 504.

As shown in FIG. 5, after receiving the notification message, thenetwork server may receive data associated with the ongoingpacket-switched communications session that is to be forwarded to thewireless terminal 400 (block 508). In embodiments of the presentinvention, upon receipt of such data, the server generates and sends outa message to the terminal from which such data was received thatnotifies the sending terminal that the wireless terminal 400 hastemporarily suspended operations with respect to the ongoingpacket-switched communications session (block 510). In other embodimentsof the present invention, the wireless terminal 400 may generatenotification messages that are forwarded directly to other participantsof the packet-switched communications session (block 512). At theconclusion of the circuit-switched call, the wireless terminal 400 maynotify the server that the temporary suspension is over and/or that thewireless terminal 400 will reinitiate its participation in thepacket-switched communications session (block 514).

FIG. 6 is a flow chart diagram illustrating operations for a wirelessterminal 400 to temporarily suspend its participation in a push-to-talksession. As shown in FIG. 6, operations may start at block 602 with thewireless terminal 400 temporarily suspending the push-to-talk (“PTT”)session for some reason (e.g., upon receipt of an incomingcircuit-switched page). The wireless terminal 400 notifies thepush-to-talk communications server that controls the push-to-talksession regarding this suspension (block 604). This notification may beforwarded before, during or after suspension of the push-to-talk sessionby the wireless terminal 400, and it may be forwarded directly orindirectly to the push-to-talk communications server. At some point(e.g., after the wireless terminal 400 terminates an incoming circuitswitched call that resulted in suspension of the push-to-talk session),the wireless terminal 400 may resume participation in the push-to-talksession (block 606).

In the drawings and specification, there have been disclosed typicalillustrative embodiments of the invention and, although specific termsare employed, they are used in a generic and descriptive sense only andnot for purposes of limitation, the scope of the invention being setforth in the following claims.

1. A method for a wireless terminal participating in a packet-switchedcommunications session to provide notice of receipt of an incomingcircuit-switched call, the method comprising: receiving a paging requestassociated with the incoming circuit-switched call; and notifying aserver associated with the packet-switched communications session thatthe wireless terminal has received the incoming circuit switched call.2. The method of Claim I, wherein notifying the server associated withthe packet-switched communications session that the wireless terminalhas received the incoming circuit switched call comprises forwarding anotification message from the wireless terminal to the server over acircuit-switched channel.
 3. The method of claim 2, wherein the incomingcircuit-switched call comprises a circuit-switched call transmitted overa GSM network, and wherein the circuit-switched channel is the SMS databearer.
 4. The method of claim 3, wherein the notification messagecomprises a text message or an e-mail message transmitted over the SMSdata bearer.
 5. The method of claim 3, wherein the notification messageis forwarded via an IP level connection over the SMS data bearer.
 6. Themethod of claim 1, wherein the notification message includes anidentification associated with the wireless terminal and/or an estimateof the length of the incoming circuit-switched call.
 7. The method ofclaim 1, wherein notifying the server comprises forwarding a messagefrom the wireless terminal to the server associated with thepacket-switched communications session.
 8. The method of claim 1,further comprising notifying the server associated with thepacket-switched communications session upon termination of the incomingcircuit-switched call.
 9. The method of claim 8, wherein thenotification forwarded upon termination of the incoming circuit-switchedcall is forwarded over a circuit-switched channel.
 10. The method ofclaim 8, wherein the notification forwarded upon termination of theincoming circuit-switched call is forwarded over a packet-switchedchannel.
 11. The method of claim 1, further comprising notifying aremote terminal that the wireless terminal has temporarily suspendedparticipation in the packet-switched communications session.
 12. Themethod of claim 1, wherein notifying the server associated with thepacket-switched communications session that the wireless terminal hasreceived the incoming circuit switched call comprises forwarding anotification message from the wireless terminal to the server over apacket-switched channel prior to answering the incoming circuit-switchedcall.
 13. A method of temporarily suspending a push-to-talk sessionestablished by a communications server between a first wireless terminaland a second wireless terminal, the method comprising: suspending thepush-to-talk session at the first wireless terminal; notifying thecommunications server that the first wireless terminal has suspended thepush-to-talk session; and then reestablishing the push-to-talk session.14. The method of claim 13, wherein suspending the push-to-talk sessionat the first wireless terminal comprises suspending the push-to-talksession in response to receiving a circuit-switched call at the firstwireless terminal over a GSM network.
 15. The method of claim 13,wherein notifying the communications server that the first wirelessterminal has suspended the push-to-talk session comprises forwarding anotification message from the first wireless terminal to thecommunications server over a circuit-switched channel.
 16. The method ofclaim 15, wherein the circuit-switched channel is the SMS data bearer.17. The method of claim 16, wherein the notification message comprises atext message or an e-mail message transmitted over the SMS data bearer.18. The method of claim 16, wherein the notification message isforwarded via an IP level connection over the SMS data bearer.
 19. Themethod of claim 13, wherein the notification message includes anidentification of a reason for suspending the push-to-talk session atthe first wireless terminal.
 20. The method of claim 13, whereinreestablishing the push-to-talk session includes the first wirelessterminal notifying the communications server that the push-to-talksession should be resumed.
 21. The method of claim 13, furthercomprising notifying the second wireless terminal that the firstwireless terminal has temporarily suspended participation in thepacket-switched communications session.
 22. The method of claim 13,wherein notifying the communications server that the first wirelessterminal has suspended the push-to-talk session comprises forwarding anotification message from the first wireless terminal to thecommunications server over a packet-switched channel before thepush-to-talk session is suspended.
 23. A method of temporarilysuspending a push-to-talk session established by a communications serverbetween a first wireless terminal and a second wireless terminal, themethod comprising: receiving notification that the first wirelessterminal has suspended the push-to-talk session; notifying the secondwireless terminal that the first terminal has suspended participation inthe push-to-talk session; and reestablishing the push-to-talk sessionwith the first wireless terminal.
 24. The method of claim 23, furthercomprising receiving notification that the first wireless terminal seeksto resume participation in the push-to-talk session.
 25. The method ofclaim 23, further comprising storing at least one push-to-talk messagereceived at the communications server that was destined for the firstwireless terminal that are received after receiving notification thatthe first wireless terminal has suspended the push-to-talk session andthen forwarding the at least one stored push-to-talk message after thepush-to-talk session is reestablished.
 26. A wireless terminal,comprising: a transceiver; and a packet-switched suspension notificationcircuit coupled to the transceiver that is configured to generate anotification message to a server controlling a packet-switchedcommunications session when the wireless terminal temporarily suspendsparticipation in the packet-switched communications session.
 27. Thewireless terminal of claim 26, further comprising a circuit-switchedcommunications circuit, wherein the packet-switched suspensionnotification circuit generates the notification message in response toreceipt of a circuit-switched page by the circuit-switchedcommunications circuit.
 28. A system for a wireless terminalparticipating in a packet-switched communications session to providenotice of receipt of an incoming circuit-switched call, comprising:means for receiving a paging request associated with the incomingcircuit-switched call; and means for notifying a server associated withthe packet-switched communications session that the wireless terminalhas received the incoming circuit switched call.
 29. A computer programproduct implemented in a wireless terminal that is participating in apacket-switched communications session that provides notice of receiptof an incoming circuit-switched call, comprising: a computer readablemedium having computer readable program code embodied therein, thecomputer readable program code comprising: computer readable programcode configured to receive a paging request associated with the incomingcircuit-switched call; and computer readable program code configured tonotify a server associated with the packet-switched communicationssession that the wireless terminal has received the incoming circuitswitched call.
 30. A system for temporarily suspending a push-to-talksession established by a communications server between a first wirelessterminal and a second wireless terminal, the method comprising: meansfor receiving notification that the first wireless terminal hassuspended the push-to-talk session; means for notifying the secondwireless terminal that the first terminal has suspended participation inthe push-to-talk session; and means for reestablishing the push-to-talksession with the first wireless terminal.